I think they are trying to rule out patients who think that all of life's problems will disappear and you will turn into Angelina Jolie and live happily ever with Brad
They assess why you have gotten to this point and try to understand your triggers. Just because you get the physical part taken care of does not mean you will be successful. You have to take care of the mental part of obesity as well. These guys really can help you work through the whys behind it.
agree with the posters above. many people use food to deal with emotional issues as well but that is something that can be tackled by a therapist who is recommended to you if you feel you need it. This is for insurance purposes and to assess you are not bulimic or a binge eater.